Research And Analysis For Aeroengine Fuel Piston Pump Kinematics And Dynamic Characteristic

Spherical swashplate axial piston pump mainly used as the fuel supply and control unit for the aeroengine, which is the important component of the engine control system, considered to be the heart of the engine and its performance influences the performance, service life and reliability of the aeroengine control system directly and then affects the flight safety of aircraft.Specific to the current problems and limitations existing in the design calculation method, this thesis takes the spherical swashplate axial piston pump as the research object, focus on the kinematics and dynamics, the features for the slipping shoe hydrostatic lubrication, movement locus of the slipping shoe ect in the pump R&D of the fundamental theories and key technologies.Regarding to the kinematics parameter calculation method, current calculation methods and its weakness are analyzed, proved that the current methods deal with non-linear displacement calculation approximately, so lead to the acceleration error around3%in typical working point. According to the piston pump kinematic theory, with detailed deduce of the current kinematics parameter calculation methods, the paper modifies and corrects the original formula, then puts forward and derives a new kinematics calculation formula based on the coordinates methods. The theoretical derivation and the simulation comparison proved that the revised methods and the new calculation method is a kind of accurate algorithm in theory.Combining the kinematics calculation analysis conclusion, this article completes the analysis of the dynamic parameters calculation for piston pump, focused on the calculation method for the cavity fuel pressure in the plunger piston, the cavity fuel pressure in the rotor, the spring force for the plunger spring and the returning plate spring, the friction on the piston cavity wall, and the inertial force caused by plunger piston involvement movement and relative motion.At the same time, as the connection component of the plunger piston, the calculation methods for the comprehensive force and the moment on the slipping shoe are analyzed. In the dynamic analysis and calculation, the result for the friction between the piston and piston cavity is determined through the nonlinear dynamic model and calculated by Genetic Algorithm.Well lubrication between the slipping shoe and the swashplate is the key technology for the piston pump design. Based on the the piston kinematics dynamics analysis, the hydrostatic lubrication principle of the slipping shoe and the self-adaptive film formation mechanism are analyzed firstly, then for the slipping shoe lubrication structure, according to the slipping shoe force balance and flow continuous theory, the calculation method for the film thickness is deduced, and last the simulation for the film thickness changing with the slipping shoe parameters and the pump working parameters is simulated.The core for the slipping shoe hydrostatic lubrication design is that how to determine the best film thickness with the corresponding less power losses and volume efficiency losses and more bearing stiffness in theory. According to this, the property theoretical for the hydrostatic lubrication film is discussed from following5parts: velocity distribution in slipping shoe film, efficiency calculation for slipping shoe throttling, the calculation for friction power losses and leakage losses caused by the hydrostatic lubrication film between the slipping shoe and the swashplate, the volume efficiency change caused by the film, the stiffness calculation for the film thickness with alternative load bearing. At the end the certain basis and specific route to determine the best film thickness is recommended.Slipping shoe is located on the return plate, and spins synchronously with the rotor. Because of the inclined piston and spherical swashplate, the slipping shoe movement locus is a gens space curve. To determine the mounting hole position and the size on the return plate is another key technology in piston pump design. Bigger hole will make the slipping shoe fall off and smaller one may jammed, the ideal shape is determined by the slipping shoe neck movement envelope curve. This article firstly analyzes the limitation for the current design methods in piston pump return plate slipping shoe mounting hole design, then according to the piston pump geometry relationship and kinematic theory, using a totally different approach, puts forward that according to plunger piston and swashplate concurrent coordinate calculation method to deduce the slipping shoe movement locus, and goes ahead to2-D and3-D trajectory simulation, and theoretically contrasts the current results, verifies the correctness of the proposed method.With the above research, in order to meet the needs of the engineering, an object-oriented universal software including piston pump performance parameter calculation, kinematics parameter calculation, dynamic parameter calculation, slipping shoe hydrostatic lubrication and film thickness calculation, slipping shoe movement analysis and simulation ect5parts is developed.The research method and the result of this thesis can be used as the basis theory for the design of the aero fuel piston pump.